You need to do a little bit of research on your particular load. You will need to know your muzzle velocity at a minimum. Check out this site, and plug in your particular numbers.
JBM - Calculations - Trajectory (Simplified)
Keep in mind however that as the environmental conditions change, so will your drop data. But use numbers that match up with an average day in your AO, and it'll get you close.
The main function of the mil dots is to determine range to the target, as long as you know the size of the object. They can be used for hold overs/unders and for movers as well, obviously. However, you just need to determine the drops for your load, and make sure that you are on the same power setting when doing this. I am of course assuming you have an SFP scope, meaning the crosshairs appear to remain the same size in the scope as power is increased or decreased. You also need to make sure of what power setting your mils are accurate on. One mil should subtend 3.6" at 100 yds. In other words, from the center of the crosshair, to the center of the first dot, either top, bottom, L or R. And also, from the center of that dot, to the center of the next dot.